Cognitive impairment and cortical degeneration in neuromyelitis optica
Annals of Neurology , 08/10/2012
Saji E et al. – The authors demonstrate cognitive impairment and substantial cortical neuronal loss with unique AQP4 dynamics in astrocytes in Neuromyelitis optica spectrum disorder (NMOsd). These data indicate pathological processes consisting not only of inflammatory demyelinating events characterized by pattern–specific loss of AQP4 immunoreactivity but also of cortical neurodegeneration in NMOsd brains.Methods
- Fourteen Japanese patients with serologically verified NMOsd, 17 patients with multiple sclerosis (MS) and 37 healthy controls were assessed with Rao's Brief Repeatable Battery of Neuropsychological Tests (BRBN).
- Using 128 tissue blocks from six other cases of NMOsd, three cases of MS, and four controls without CNS involvement, the authors performed quantitative analysis of cortical neuronal loss and layer-specific changes in NMOsd.
- In BRBN assessments, 57% of NMOsd patients and 47% of MS patients had impaired performance on at least three cognitive tests.
- Cognitive impairment in NMOsd was common even in the limited form of disease, indicating that NMOsd may progress insidiously from early stages of disease.
- Neuropathological assessments showed neuronal loss in cortical layers II, III, and IV with nonlytic reaction of aquaporin-4 (AQP4)-negative astrocytes in layer I, massive activated microglia in layer II, and meningeal inflammation in NMOsd brains.
- All NMO cases showed no evidence of cortical demyelination.